In manufacturing processes and general industry activities, many machines are operated by air cylinders and air control valves which direct air to the cylinders. These air cylinders may be power operated in one direction with gravity or spring return, or may be power operated in each direction. On some occasions, it is necessary to stop the machines for repairs. Under these circumstances, it is important that a master control valve or other valves be closed to cut off air supply. It is not uncommon to lock these valves in the "off" position with a padlock so that no accidental start-up can occur while the particular machine is being worked on.
The present invention is directed to a lock-out shut-off valve which can be manually operated to a shut-off position and locked with the passage of a padlock link through the valve shaft. The invention is further directed to a shut-off valve which when released from the lock-out position will control the restart pressure in a manner to prevent a sudden charge of air to the cylinders of the machine. In some cases, the shut down may have caused some cylinders to move from an end position or to retract entirely and a slow reset is desirable to avoid injury or accidents.
Additional features and objectives of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with details to enable persons skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the invention.